Sheet cleaning machines



Feb. 19, 1957 w. l. PHILLIPS ETAL 2,781,535

SHEET CLEANING MACHINES Filed May 7, 1954 5 Sheets-Sheet l INVENTORS.MLL/AM 1 PH/LA/Pfi' BY JAMES a zAwe /vfl' Feb. 19, 1957 w. l. PHILLIPSET AL SHEET CLEANING MACHINES 5 Sheets-Sheet 2 Filed May 7, 1954INVENTORS MLL/AM Z PH/LL/P6' 17 1 455 C. LAWeENaE A r roe/V5145 Feb. 19,1957 w. l. PHILLIPS ETAL 2,781,535

SHEET CLEANING MACHINES Filed May 7, 1954 5 Sheets-Sheet 3 III"-INVENTORS. WILL/AM I. PHILLIPS J/m s' a LAWEL-NC'E BY WMaW A r roe/w y:

Feb. 19, 1957 w. I. PHILLIPS ET AL ,78 35 SHEET CLEANING MACHINES FiledMay 7, 1954 5 Sheets-Sheet 4 INVENTORS. W/LL/AM l. PH/LL/P' BY J4M5mama/a? \o \Q I l A TTOEA/E V5 United States Patent SHEET CLEANINGMACHINES William L Phillips and James C. Lawrence, Seattle, Wash.,assignors to C & H Supply Company, Seattle, Wash, a corporation ofWashington Application May 7, 1954, Serial No. 428,158

6 Claims. (Cl. -77) The purpose of the machine to which the presentinvention pertains is the removal of smut from sheets of material passedthrough it and is concerned particularly with the removal of smut suchas masking ink from relatively small sheets of material.

The present machine was designed particularly to solve the problem ofremoving masking ink from small sheets of aluminum foil, one foot to oneand one-half feet square, for example, utilized in the process of makingmetal foil labels, but the machine is not restricted to cleaning sheetmaterial either of that type or that size. The construction andoperation of the machine will, however, be described in connection withsuch a process.

A principal object of the invention is to clean such sheets, includingfeeding them to the cleaning machine, washing, scrubbing, rinsing anddrying the sheets, and finally accumulating them, all without manualhandling.

A further object is to utilize cleaning liquid efiiciently in thecleaning operation so that it will be sprayed directly upon each sheet,particularly for initial washing and rinsing, by timing the actuation ofthe sprays and travel of the sheet accurately, and arranging the flow ofcleaning liquid so that rinsing of the sheet is accomplished with thecleanest liquid but initial washing will not utilize perfectly cleanliquid. Conveniently, the cleaning liquid can be reconditioned forrecirculation through the machine.

In the cleaning procedure it is an object to scrub each sheet firmly,though perhaps lightly, despite'the flimsy character of the sheetmaterial.

Another object is to dry the sheet material after the rinsing operationduring its travel through a short distance to keep the machine compactwhile moving each sheet at the same speed of travel as it moves duringthe washing and rinsing operations. f

An additional object is to segregate the rinsing liquid from the washingliquid eifectively despite uninterrupted movement from the scrubbingstation to the rinsing station, so that the sheet will emerge as cleanas possible with minimum reconditioning of the cleansing liquid.

A machine capable of accomplishing the foregoing objects may incorporatea sheet transport conveyor which will grip the leading edge of eachsheet as it is fed automatically to such conveyor and will convey thesheet first through a washing station, then through a scrubbing station,next through a rinsing station, and finaly through a drying station, inseries. Smut washing liquid or solvent will be sprayed on the sheet asthe sheet passes the washing station and the rinsing station, and thespray will be interrupted as soon as the sheet has passed to conservethe solvent. The drying is accomplished by passing the sheet betweensqueegee rolls.

Additional objects and advantages of the machine will be discussed inthe following detailed description of the preferred type of'machineillustrated in the drawings.

Figure 1 is a side elevation view of the sheet cleaning machine, andFigure 2 is a somewhat diagrammatic vie of the machine incorporating apiping diagram.

v 2,781,535 Patented Feb. 19, 1957 ICC Figure 3 is an enlarged sideelevation view of the central portion of the cleaning machine with partsbroken away, showing the scrubbing mechanism, and Figure 4 is a topperspective view of one portion of the machine with parts broken away toreveal scrubbing mechanism.

Figure 5 is a top perspective view of the section of the machineincorporating the rinsing mechanism, parts being broken away.

Figure 6 is a top perspective view of the section of the machineincorporating the drying mechanism and having parts broken away.

Figure 7 is a side elevation view of the same portion of the machinewith parts broken away.

The sheet cleaning machine includes five principal sections, shown inFigure 1, namely an automatic feeding section 1, an initial washingsection 2, a scrubbing section 3, a rinsing section 4 and a dryingsection 5. Through all of these sections sheets S are moved withoutinterruption by a sheet conveyor 6. While the machine may be used forother purposes, it is very useful for removing from aluminum foil sheetssmut in the form of masking ink, which is applied to the aluminum foilin the process of making aluminum foil labels.

In general the process of making such labels includes anodizing a sheetof "aluminum foil of approximately .003 inch in thickness, dyeing theanodized foil surface and maskingwith printers ink by a silk screenprocess the background of the sheet, etching the unmasked portions ofthe sheet to remove the color in the indicia portions, and then removingthe maskingink. This ink is tenacious in its adherence to the sheetsurface and is very messy to wash oil with ink solvent. Moreover, suchaltuninum foil sheets are rather fragile so that caremust be exercisedin handling them while scrubbing the masking ink from their surfaces. Bythe use of the present machine cleaning of the sheets can beaccomplished by production line technique which is entirely automatic,and at the same time is considerably more etficient than hand methodsand conserves cleaning liquid.

The smut covered sheets are stacked on the feeding platform 10 of theautomatic sheet feeding device 1,

which is a conventional printing press feeding device and tween them.The gripping bars are spaced apart along the conveyor far enough toleave ample clearance between successive sheets, but the particularspacing of such sheets is not of special significance. Various pro"-essing operations are coordinated with the sheet location so thatsuccessive treatments of each sheet occur in timed sequence. V i

In cleaning the smut from aluminum foil sheets of the type described, anink solvent is used as the washing liquid. The first step in thecleaning process, therefore, is to spray on the ink-coated side of eachsheet solvent which will begin to dissolve the ink. This initial washingspray operation occurs'in the washing section 2 of the processing tank,which preferably is closed onall sides except where the sheet-enters thetank at the feed end and is removed from the spray head only duringpassage of a sheet beneath it.

The processing tank as a whole includes raised feed and discharge endportions and a depressed central portion. All the liquid, therefore,tends to flow from the spray section down the inclined portion 23 to thecentral depressed portion. The conveyor 6 follows this path, beingguided over guide sprockets 61 in the sheet feeding mechanism (Figure1), then over sprockets 62 at the junction between the elevated feed endand the portion inclined downwardly in the direction of travel to thecentral depressed portion, and under sprockets 63 at the lower end ofsuch inclined portion.

The fingers of the clamps on the gripping bars 60 are arranged insubstantially coplanar relationship with the chain of the conveyor 6 andare long enough to exert a firm grip on the leading edge of an aluminumfoil sheet despite the fragile nature of such sheet. As thechain passesfrom the downwardly inclined trough portion of the device, therefore, toits lowermost horizontal trough portion, the sheets S will trail behindbar 60 in generally horizontal position. In this scrubbing section 3 ofthe trough is at least one, and preferably two scrubbing stationsthrough which the conveyor passes.

Each scrubbing station is separately covered by a hood 30 and includes arotary brush 31 and a cooperating backing roll 32. The chain of theconveyor 6 passes over the backing roll. which has the upper portion ofits periphery generally in horizontal alignment with an entranceaperture 33, through which the conveyor chain enters the housing 30, andan exit aperture 34. through which the chain of the conveyor leaves thehousing. The backing roll is mounted on an axle 35 which also carries atopposite ends of the roll 32 sprockets 36 with which the conveyor chainsengage to turn the backing roll 32.

The brush 31 is 'driven preferably by a motor 37 independent of theconveyor drive in a direction opposite the direction of rotation of thebacking roll 32, so that the lower periphery of the brush moves in adirection counter to the direction of travel of the conveyor 6 and thefoil sheets carried by it. Normally the smut is on only one side of thesheets being processed, which will face upwardly so that it issufiicient for the scrubbing brush to contact only the upper face of thesheet. The speed of the motor 37, the drive ratio between such motor andthe brush 31, and the diameter of the brush may be selected to efi'fectbrushing movement of the lower brush periphery at any speed desiredwithin wide limits.

As the foil sheets are drawn across the periphery of the backing roll32,pressure of the brush on the upper sides of the sheets will notappreciably deflect the sheets or subject them to mutilating stressesWhile exerting an effective scrubbing force on the sheets. To accomplishthis action it is necessary that the shafts of the backing roll and therotary brush be located sufiiciently close together to effect anappreciable positive pressure of the brush against the backing roll or apiece of aluminum foil on it.

It is undesirable, however, for the sheet clamping bar 60, which isconsiderably thicker than the foil sheets, to be subjected to suchvigorous scrubbing action and consequently the backing roll 32 has in ita longitudinal groove 38 of a width to receive such bar. Thecircumferential extent of the rollers 32 will be coordinated with thespacing of bars 60 along the conveyor chain so as to insure that eachclamping bar will always register with a. groove 38, although it is notnecessary that the conveyor have a clamping bar for each increment oflength equal to the The bar spacing and sprayed with ink solvent. Ifdesired, this washing section of the machine may contain sutficientsolvent so that the foil actually is moved through a solvent bath duringthe brushing operations, but this may be unnecessary.

From the washing section the foil ascends through the upwardly inclinedrinsing section 4 shown best in Figure 5 and then into a drainingsection. In the rinsing section the sheet S is carried between upper andlower rinsing spray pipes which spray ink solvent on the sheet.Preferably this section includes a plurality of upper spray pipes 40 anda plurality of lower spray pipes 41 which project spray onto both sidesof the foil sheet to rinse otfthe dirty solvent.

Through this section extend upper wires 42 and lower wires 43 reasonablyclose to the conveyor 6 which restrict the fluttering movement of thefoil sheets under the impact of the spray projected on them from thepipes 40 and 41. A plurality of these wires may be supported atintervals spaced transversely of the direction of movement of theconveyor by suitable mounting lugs 44 mounted on the partition walls 45forming the opposite ends of the rinsing compartment. The conveyor movesthe sheets into this compartment through an entrance opening 46 and outthrough a discharge opening 47. A window 48 may be incorporated in theside of the apparatus at the location of the rinsing chamber to enablean operator to observe the effectiveness of the apparatus at this pointin completely cleaning the smut from the sheet.

After the sheet is rinsed it is carried on up the incline by conveyor 6,during which travel most of the rinsing liquid drains from the sheet.Such liquid, as well as that sprayed onto the sheet in the rinsingcompartment, flows down the inclined bottom trough and through limberholes in the corners of the partitions 45 toward the washingcompartment.

When the foil sheet reaches the drying compartment 5 shown in Figures 6and 7, its path of movement preferably changes from upwardly inclined tosubstantially horizontal. The sheet moves into the drying compartmentthrough the aperture 50 in the partition 51 which serves principally tostiffen the body of the apparatus. In the drying compartment is mountedthe terminal shaft 64 of the conveyor 6 which preferably is the poweredshaft to pull the conveyor chain by rotation of sprockets 65 over whichsuch chain passes. The shaft may be driven by sprocket 66, turned bychain 67, which is driven by the motor 68 shown in Figure 1. Thisterminal shaft of the conveyor is reasonably near the entrance to thedrying chamber.

From the end of conveyor 6 to the accumulating bin 7 the foil sheets aremoved by a mesh belt conveyor 52, which uuderlaps' the discharge end ofconveyor 6, The foil sheets must, of course, be released from theclamping bars in order to be carried by the conveyor 52, and such sheetreleaseis eitected by a'stationary cam 69 which is engaged by a camfollower roller 69 carried by the clamp releasing arm of the clamp bar60. The cant 69 is located adjacent to the return run of the conveyor 6spaced slightly from the conveyor terminal shaft 64. Thus each foilsheet will be held clamped by its bar 60 until after the bar hastraveled around the sprockets and the foil sheet S has been flippedbeneath the conveyor by such action.

Because the sprockets 65 should be of considerable diameter as apractical matter, if a foil sheet were released while being carried bythe upper stretch of conveyor 6, it would fall through a considerabledistance before reaching the mesh conveyor 52 located beneath thesprockets 65. Also, if a foil sheet were released while being carried bythe upper stretch of the conveyor, it would be necessary to release itwell before the sheet reached the shaft 64 because otherwise the sheetwould strike such shaft. Also there is a possibility that it wouldstrike a clamping bar 60 on the lower stretch of the conveyor 6. Byreleasing the foil sheet when moving along the lower stretch of theconveyor rather than the upper stretch, the distance which the sheetmust drop to the mesh conveyor 52 is kept to a minimum. Also, there isno possibility of the released sheet striking any interfering mechanismsuch as a clamping bar 60 or the shaft 64 during its travel to the meshconveyor belt.

While the conveyor 52 has been described as a mesh conveyor belt, adifferent type of conveyor belt could be used if desired. The principalpoint of importance, however, is that the conveyor 52 atford a movingsurface on which the foil sheet can lie for translation edgewise withoutbeing positively gripped in any fashion as it is when moved by theconveyor 6. The foil sheet transportation of this type is desirable sothat the conveyor 52 can not only carry the sheet to but feed itedgewise between cooperating resilient surface squeegee rolls 53 locatedim mediately beyond the discharge end of the conveyor 52. The enteringangle between these rolls should be sub stantially in alignment with theupper surface of the conveyor 52, as shown best in Figure 7.

The rolls 53 have their opposite ends mounted in a double pillow blockmounting so that the roller shafts are held at a spacing to press theroll peripheries tightly together. As the sheet S moves edgewise betweenthese rolls, therefore, all the ink solvent remaining on the foil sheetwill be squeezed off it, so that the sheet emerges in a substantiallydry condition and is discharged from the machine ready for storage orimmediate further processmg.

It will be evident that belt 52 should not be driven appreciably slowerthan conveyor 6 unless there is considerable space between the clampbars 61) of that conveyor. In any event it is essential that the speedof the conveyors 6 and 52 be coordinated to prevent the possibility ofexcessive accumulation of foil sheets on the latter. Such coordinationcan be effected most easily by driving the conveyor 52 from the driveshaft 64 of conveyor 6. The peripheral speed of the squeegee rolls 53should also be substantially the same as the speed of conveyor 52, andit likewise may be driven from the drive shaft d4 of conveyor 6. Thedrives for rolls 53 and conveyor 52, then, may include the chain 55'interconnecting a sprocket 56 on drive shaft 64 and a sprocket 57secured on the shaft of the lower squeegee roll. A chain 58 connects asprocket at the other end of the lower squeegee roll to a sprocketintegral with the roll 59 at the discharge end of belt conveyor 52.

In many cases the foil sheets S may be curled to a greater or lesserextent, and to insure reliability of their feed edgewise into the anglebetween the squeegee rolls, it is desirable to provide at least one andpreferably a plurality of confining chains located above the carrierbelt 52. While stationary guides probably would be of considerableassistance in this regard, movable confining elements such as the chains70 are considerably more effective. The stretch of each of these chainsadjacent to the upper surface of the carrier belt 52 is inclined towardthe carrier belt in the direction of its movement.

A convenient and compact arrangement is to slope the upper stretch ofconveyor 52 upward from beneath the discharge end of the conveyor 6 to alocation adjacent to the infeed side of the squeegee rolls. Theconfining elements "7%) may then be inclined downward somewhat in thedirection of their movement, as indicated in Figure 7, to form a passageconvergent toward the entering angle of the squeegee rolls through whichthe foil sheets move.

(Jurled portions of the foil sheets engaged on opposite sides by theconfining elements and by the conveyor 52 are gradually flattened untilthey are sufiiciently flat upon reaching the squeegee rolls as to be fedcertainly between them. Since the squeegee rolls turn in oppositedirections, as indicated in Figure 7, contact of the leading edge of afoil sheet with the rolls also will have the tendency to move the sheetedge into the angle between the rolls.

If the confining elements 70 are of the movable type,

it is desirable for the confining members and. the carrier conveyor 52to move at substantially equal speeds; the drive of the confiningchains, like the drive for the conveyor 52, may therefore come from thesqueegee rolls 53. The particular arrangement shown incorporates a chain71 powered by a sprocket 72 on the upper squeegee roll shaft whichdrives a sprocket 73 on the discharge end shaft 74 of the confiningchains. This shaft carries sprockets 75 over which the confining chainsrun, and the opposite ends of such chains are carried by sprockets 76 onshaft 7'7. The degree of convergence between the confining elements 70and the upper stretch of coin veyor 52 can, of course, easily'be alteredby shifting the position of shaft 77 upward or downward.

Since the ink solvent utilized in'the operation of the machine describedis rather expensive, it is desirable to use as little of such solvent aspossible to do a thorough cleaning job. On the other hand, ifthe foilsheets were simply run one after another through a solvent bath whichwas only changed periodically, the thoroughness of the cleaning jobwould decrease continually until the cleaning operation did not givesatisfactory results. Use of cleaning fluid is most effective at certainstages of the entire cleaning operation, and solvent could be conservedif it were used only at such selected points of the cleaning cycle. Whenall these factors are considered, however, too much solvent still isrequired to make the automatic cleaning operation economical, becausewhen the cleaning operation is done by hand the operator can observewhen the cleaning solvent being used becomes too dirty for continued useand can change it.

in the present machine, therefore, its operation is made practical,first by recovering used solvent by cleaning it; second, by supplyingsolvent only at the locations where it is most effective; third, bysupplying such solvent at such locations only while a foil sheet ispassing the particular solvent supplying station; and, fourth, cleansolvent is used only for the final rinsing operation, and somewhatsoiled solvent is employed for the initial stages of the cleaningoperation. in order to accomplish this type of solvent utilizationtiming mechanism is provided which is coordinated with movement of thesheet conveyor so that the duration of the solvent dispensing action ateach location is closely controlled.

The first soaking or washing spraywhich is delivered 7 by the head 24!can utilize reasonably dirty solvent and still be effective. Likewise,the additional washing spray 39 shown in Figure 3 can eject reasonablydirty solvent because these follow immediately a scrubbing operation ineach case, so that they will float off smut mechanically and use thesolvent properties primarily to dissolve this loosened smut to preventthe ink being deposited at the bottom of the trough. On the contra y,the solvent delivered to the final rinsing sprays '48 and 41 should beclean, although it may be recovered and recirculated solvent. 7

in Figure 2 the piping for the solvent is shown which delivers somewhatdirty solvent to the spray pipes 25) and 39, clean solvent to therinsing spray pipes 40 and 41, removes used solvent from variousportions of the tank and purifies the solvent forreuse. Startingwith theclean solvent in tank 8, a pump 80 delivers such solvent through pipe 81to the rinsing spraypipes A li-and 41 from which the clean solventissprayed onto scrubbed foil sheets, as described above. This liquiddrains through the limber holes 49 of the partitions 45, as mentioned,into-a sump formed at the upper side. ofpartition 82, as shown in Figure3. somewhat dirty solvent is withdrawn by gravity through pipe 83 intoan intermediate storage tank 34.

From thetank 34 a pump 85 delivers the somewhat From this sump the ofthe tank to the central sump to which drain pipe 87 is connected. Sincethere are only three washing heads as compared to six rinsing pipes, itis probable that the rate at which rinsing solvent is used will exceedthe rate at which the washing solvent is dispensed. Consequently, tank84 would tend to receive partially used solvent at a rate faster thansuch solvent is withdrawn by pump 85. Any excess solvent thusaccumulated in tank 84 flows out of it through the overflow pipe 88 intothe pipe 87 mentioned above.

From pipes 87 and 88, the former of which collects very dirty solvent,the pump 89 delivers the dirty solvent through pipe 9 to the feed end ofthe solvent cleaner 90. r

The solvent cleaner 90 may be of any conventional evaporatorconstruction and consequently is shown merely diagrammatically in Figure2. As solvent continues to be pumped into the cleaner and is purified,it will overflow through pipe 91 and flow by gravity to the cleansolvent supply tank 8. The tanks 8 and 84 will, of course, be ofadequate capacity to hold enough cleaning solvent for operating thewhole system when all the solvent has been drained from the tank inwhich the foil sheets are cleaned.

As mentioned previously, in order to conserve solvent it is desirable todispense such solvent both at the washing stations and at the rinsingstations only at the time and for the duration during which a sheet offoil is being moved past such respective stations by the conveyor 6. Toeffect this operation the several spray pipes are controlled bysolenoid-operated valves which are energized by switches of cam timingmechanism. Such cam timing mechanism shown in Figures 1 and 3 iscoordinated with the movement of conveyor 6 carrying the sheets.

The spray timing mechanism includes rotary cam means preferablyincorporating two can disks 100 and 101 mounted in coaxial side-by-sideposition on shaft 102 for rotation. These cam disks are driven by achain 103 from sprocket 63 which is turned by movement of conveyor 6.Around the periphery of these cams are arranged solenoid valve controlswitches including switch 104 for the initial washing operation, switch105 controlling dispensing of washing solvent at the scrubbing stations,and switches 106, 107 and 108 which respectively control the rinsingsprays.

The circumferential extent of the cam ridges with which the switchplungers engage determines the duration of solvent dispensing duringeach cycle. The circumferential location of such ridges establishes thepoint at which each spray operation begins and terminates. In order toselect proper peripheral lengths of the cam ridges to elfect the desiredcontrol operation, the two cams 100 and 101 are arranged in side-by-siderelationship, the former being engaged by the washing spray controlswitches 104 and 105 and the latter being engaged by the rinsing controlswitches 106 and 107. The switch 104 will be electrically connected toenergize the solenoid of valve 22, and the switch 105 will beelectrically connected to energize the solenoids of valves 109 whichcontrol the flow of solvent to the washing spray pipes 39 at thedischarge side of the scrubbers. Switches 106, 107 and 108 areelectrically connected respectively to the solenoids of valves 110, 111and 112. Valve 110 controls the flow of solvent to the lowest pipe 40and the lowest pipe 41, valve 111 controls the flow of solvent to theintermediate pipe 40 and the intermediate pipe 41, and valve 112controls the flow of solvent to the highest pipe 40 and pipe 41.

From Figure 3 it will be seen that the sheets S moving in the directionindicated by the arrow are approaching the washing sprays 39.Correspondingly, the leading end of the cam rib on cam disk 100 isapproaching the control switch 105 for the valves controlling the flowof solvent to pipes 39. As soon as the 11b of cam 100 rides under theplunger of switch 105, the switch will be moved from its normally openposition into closed position, valves 109 will be opened, and solventwill be sprayed from pipes 39 onto the foil. Such dispensing of thespray liquid will continue until the switch plunger rides off the rib ofearn 100, whereupon the trailing edges of the two sheets which have justemerged from the scrubbers will have passed beyond the respective spraypipes 39.

Before the sprays from pipes 39 have been shut off the rib of cam willhave moved under the plunger of switch 104 to close this switch foreifecting energizetion of the solenoid valve 22 initially to spraywashing fluid on another foil sheet just entering the machine. Becausethe same cam rib actuates switch 104 as actuates switch 105, the initialspray will continue for the same duration as the sprays from pipes 39.Also, the switch 104 will be placed at the proper location around theperiphery of cam 100 so that the spray will start just before the sheetreaches the spray location and will be stopped as soon as the sheetleaves such location.

The position of the cam disks shown in Figures 1 and 3 does notcorrespond to the position of the sheet S shown in Figure 5. None of theswitches 106, 107 and 108 is engaged by the rib of cam 101. As this camis turned during approach of a sheet S to the rinsing spray section,however, the leading end of the rib on earn 101 will move beneath switch106 to energize valve 110 and start the first sprays. As the sheet andcam continue to move, the leading end of the rib on cam 101 will moveunder the plunger of switch 107 to close such switch just before theleading edge of the sheet reaches the intermediate spray pipes.Similarly, the leading edge of such cam rib will move under the plungerof switch 108 as the leading edge of the sheet approaches the finalspray pipes. The rib of cam 101 is of suificient circumferential extentthat all three of the switches 106, 107 and 108 will be closed for ashort time, so that all six rinsing sprays will be projected for acorresponding period onto the sheet. As rotation of the cam 101continues, first switch 106, then switch 107 and finally switch 108 willbe opened as they ride off the cam rib, so that successively the first,intermediate and last pair of upper and lower rinsing sprays will bedeenergized as the trailing edge of the sheet leaves each pair ofsprays.

The aluminum sheet being cleaned may in some instances be sufiicientlystiff to be suspended in substantially horizontal planar attitude whensupported in cantilever fashion by one edge. The foil which the presentdevice may be used to clean, however, is only .003 of an inch thick, sothat a sheet a foot or so square, when held in cantilever fashion by oneedge, would droop very considerably. Consequently, the conveyor 6includes chains spaced apart a distance substantially equal to the widthof the sheet being cleaned, as shown in Figure 5 and Figure 6, and sheetsupporting rails are provided between these chains to support the foilsheets in generally planar shape. In Figure 3 the rails 113 support thesheet as it moves downward to the scrubbing stations, and between thesestations the sheet is supported by the rails 114 which are shown both inFigure 3 and in Figure 4. Between the last scrubbing station and therinsing station the sheet is supported by the rails 115, and the rails116 shown in Figures 5 and 6 support the sheet between the rinsingsection and the drying section 5.

We claim as our invention:

1. A sheet cleaning machine comprising a tank, conveying means operableto' move a sheet edgewise through said tank in succession through aninitial washing station,

a scrubbing station, a rinsing station, and a drying station,

means at such initial washing station operable to supply liquid to thesheet, scrubbing means at the scrubbing station operable to engage andscrub the sheet during its movement by said conveying means, sprayingmeans at said rinsing station operable to rinse the sheet, drying meansat the drying station operable to remove moisture from the sheet, andtiming means operable by said conveying means to initiate operation ofsaid spraying means at the rinsing station substantially when such sheetreaches the rinsing station and further operable to terminate suchoperation of said spraying means substantially when such sheet leavesthe rinsing station,

2. A sheet cleaning machine comprising conveying means operable to movea sheet edgewise through a spraying station, spraying means at saidspraying station operable to spray liquid on the sheet, and timing meansoperable by said conveying means to initiate operation of said sprayingmeans substantially when such sheet reaches the spraying station andfurther operable to terminate such operation of said spraying meanssubstantially when such sheet leaves the spraying station.

3. A sheet cleaning machine comprising a tank, first conveying meansoperable to move a sheet edgewise through said tank and including chainsspaced apart a distance substantially equal to the width of the sheettransversely of said chains, a clamping bar having its opposite endsconnected to said chains, respectively bridging between them andoperable to clamp the leading edge of the sheet, squeegee rolls beyondthe discharge end of said conveying means, and second conveying meanshaving one end underlapping the discharge end of said first conveyingmeans and operable to underlie substantially the entire area of a sheetdischarged by said first conveying means and operable to drivinglyengage only the under surface of the sheet while the upper surface ofthe sheet is substantially free of driving engagement, to transport sucha sheet to said squeegee rolls and into tractive engagement therewithfor movement between said squeegee rolls to dry the sheet.

4. A sheet cleaning machine comprising a tank, first conveying meansoperable to move a sheet edgewise through said tank and including chainsspaced apart a distance substantially equal to the width of the sheettransversely of said chains, a clamping bar having its opposite endsconnected to said chains, respectively, bridging between them andoperable to clamp the leading edge of the sheet, squeegee rolls beyondthe discharge end of said conveying means, and mesh belt conveying meanshaving one end underlapping the discharge end of said first conveyingmeans and operable to receive a sheet discharged by said first conveyingmeans and operable to drivingly engage only the under surface of thesheet while the upper surface of the sheet is substantially free ofdriving engagement, to transport such a sheet to said squeegee rolls andinto tractive engagement therewith for movement between said squeegeerolls to dry the sheet.

5. A sheet cleaning machine comprising a tank, conveying means operableto move a sheet edgewise through said tank in succession throughawashing station and a rinsing station, washing spray means at suchwashing station operable to spray cleaning liquid on the sheet duringmovement thereof through the Washing station by said conveying means,rinsing spray means at such rinsing station operable to spray rinsingliquid on the sheet during movement thereof through such rinsing stationby said conveying means, washing spray solenoid valve means operable tocontrol operation of said washing spray means, rinsing spray solenoidvalve means operable to control operation of said rinsing spray means,rotary cam means driven by said conveying means in synchronismtherewith, and switching means actuated by said rotary cam means andoperable to control energization of said washing spray solenoid valvemeans and of said rinsing spray solenoid valve means to effectenergization thereof only substantially during movement of the sheet bysaid conveying means through the washing station and through the rinsingstation, respectively.

6. In a sheet cleaning machine, a plurality of spray means arranged inseries, conveying means operable to move a sheet edgewise past the spraymeans of such series in sequence, a plurality of solenoid valves one foreach of said spray means and operable to control each such spray meansindependently of the other spray means, rotary cam means driven by saidconveying means in synchronism therewith, and switching means actuatedby said rotary cam means and operable to energize said solenoid valvesin sequence and to deenergize said solenoid valves in sequence to effectenergization of each spray means substantially only during movement ofthe sheet past such respective spray means.

References Cited in the file of this patent UNITED STATES PATENTS1,039,608 Spiess Sept. 24, 1912 1,943,775 Taylor Jan. 16, 1934 2,184,567Rundell Dec. 26, 1936 2,313,606 Webb et al Mar. 9, 1943 2,372,599Nachtman Mar. 27, 1945 2,374,668 Davidson May 1, 1945 2,380,550 ReedJuly 31, 1945 2,392,391 Kaddeland Jan. 8, 1946 2,467,423 Bruker Apr. 19,1949

